Do these numbers look right?

buzzinhalfdozen · 04-04-2014, 10:42 AM

Ok, Bobby how bout this. Where is your MAP located..in the ECU or out, in either case why don't you try this. Disconnect the vacuum hose from the engine that hooks to your MAP sensor install a hand operated vacuum pump and pull a vacuum on sensor to around 40ish PKA see how your Pulse width responds, it should go down. Looks like the MAP is very high in the idle shot you posted, other than that and the fact your P.W. looks extremely high the rest looks normal to me. Another check is to use your vacuum pump and pull a vacuum...read the gage (on the pump) and see if it is close to what your ECU is reading. this should tell you if the MAP is skewed or not. Please try this if you can and let us know the results. Not knowing your set up (engine size, injectors cam, ect.) I'm merely guessing but I'd expect to see maybe 2.9-3.? M.S. of pulse width at idle. Again good luck. Joe, Bobby I also noticed you have nearly 2 volts difference in batt. voltage. Though I don't believe that is causing the issue you have you need to be aware that voltage has a direct effect on the injector "on time" just something to think about. On another note does your ECU have any type of "blending function" to blend between the TPS and the MAP sensor to correct for poor MAP signal @ idle?

04-04-2014, 10:42 AM	#11
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 984 Likes: 0 Liked 11 Times in 8 Posts	Re: Do these numbers look right? Ok, Bobby how bout this. Where is your MAP located..in the ECU or out, in either case why don't you try this. Disconnect the vacuum hose from the engine that hooks to your MAP sensor install a hand operated vacuum pump and pull a vacuum on sensor to around 40ish PKA see how your Pulse width responds, it should go down. Looks like the MAP is very high in the idle shot you posted, other than that and the fact your P.W. looks extremely high the rest looks normal to me. Another check is to use your vacuum pump and pull a vacuum...read the gage (on the pump) and see if it is close to what your ECU is reading. this should tell you if the MAP is skewed or not. Please try this if you can and let us know the results. Not knowing your set up (engine size, injectors cam, ect.) I'm merely guessing but I'd expect to see maybe 2.9-3.? M.S. of pulse width at idle. Again good luck. Joe, Bobby I also noticed you have nearly 2 volts difference in batt. voltage. Though I don't believe that is causing the issue you have you need to be aware that voltage has a direct effect on the injector "on time" just something to think about. On another note does your ECU have any type of "blending function" to blend between the TPS and the MAP sensor to correct for poor MAP signal @ idle? __________________ Joe Buchanan SS/BX 3117 Last edited by buzzinhalfdozen; 04-04-2014 at 01:01 PM.